Water conservation and reuse strategies
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Water Conservation &Reuse Strategies for Southern California
Rosalind Haselbeck , PhD, LEED APBuilding Green Futures Inc.
LUNCH + LEED
July 15, 2010
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Learning Objectives
1. Apply the historical context to our current water crises, both globally and here in San Diego.
2. Identify strategies to reduce indoor water use.3. Discuss the basic features of a rainwater
harvesting system including benefits, components, and estimating supply and demand.
4. Develop an outside water usage and conservation strategy.
5. Identify resources to support water conservation and rainwater/graywater systems.
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www.zmescience.com/.../2009/08/water_b.jpg
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Historical Context
• How We Use Water
• The Water Cycle and Urbanization
• Water Usage in San Diego
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Water FootprintItem Gallons to
produce
Glass of Milk 52
Cup of Coffee 37
1 Apple 19
Cotton T shirt 530
Hamburger 635
Meat-based diet 1320/day
Vegetarian diet 687/day
Source: United Nations Development Report, 2006
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Location Water useGPC/day
San Diego 164
US average 152
Japan 99
Germany 51
Nigeria 10
Uganda 4
Water scarcity <13
Water Usage
Source: SDWA Annual Report 2009
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How We Use Water
• “Reducing potable water demand by 10% could save approximately 300 billion kilowatthours of energy each year” (Michael Nicklas, Rainwater, High Performance Buildings, Summer 2008).
• Use of potable water– Single vs. multi-use– Need for potable water indoor applications– According to the EPA, 80% of indoor use doesn’t
require potable (Municipal Handbook Rainwater Harvesting Policies, 12/08)
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Water Run-off: developed vs. natural
Source: http://www.coastal.ca.gov/nps/watercyclefacts.pdf
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Source: http://www.epa.gov/volunteer/stream/vms21.html
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History of Water Usage in San Diego
Old Mission Dam; completed 1815 San Vicente reservoir; 1947
Source: San Diego County Water Authority(http://www.sdcwa.org/about/who-history.phtml)
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Source: SDWA Annual Report 2009
“Water conservation is the cheapest new source of water”--SDWA, ‘07
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Indoor Water Usage
• Water usage and fixture choices
• Water reuse for indoor applications
• LEED credits for Water Efficiency
• Standards for indoor rainwater usage
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Source: American Waterworks Association Research Foundation (AWWARF) Residential End Uses of Water, Denver, CO; 1999
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Annual Indoor Water UsageVery High Efficiencyf vs. Standard**
Fixture Average # uses per day per person*
Typicalfixture (gal or min)**
Gallonsper person per day
Gallonsper yearfamily of 4
Very hi efficiency fixture(gal or min)f
Gallonsper person per day
Gallons per yearfamily of 4
Toilet 4 1.6 gpf 6.4 9,344 1.1 gpf 5.2 7,592
Lavatoryfaucet
5 2.2 gpm0.5 min
5.5 8,030 1.5 gpm0.5 min
3.75 5,475
Shower 1 2.5 gpm6.3 min
15.75 22,995 1.75 gpm6.3 min
12.6 18,396
Clotheswasher
7 per wkFamily*
55 gal* 20,020 (25 gal) 9,125
Total 60,389 42,413
* Source: http://www.csgnetwork.com/waterusagecalc.html** Source: EPAct 1992; http://www.epa.gov/watersense/docs/matrix508.pdff Source: LEED-H Reference Guide WE 3.2; 2008
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WE (min 3 pts) Credit Points
WE 1: Water Reuse5 points max
1.1 Rainwater Harvesting SystemAnd/or
4 points outdoor + indoor (>50% roof)
1.2 Graywater 1 point
OR1.3 Municipal Recycled Water
3 pts max if use instead of1.1-1.2
WE 2: Irrigation 2.1 Hi-efficiency 3 points max
4 points max 2.2 3rd party 1 point max
OR 2.3 Reduce irrigation demand
4 points max
WE 3: Indoor Water Usage
3.1 Hi-efficiencyfixtures/fittings
3 points if all fixtures
6 points max 3.2 Very hi-efficiency 6 points max
WE Credits for LEED-Homes: Maximum 15 points possible
Source: USGBC LEED for Homes Rating System, 2008
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WE (min 3 pts) Credit Points
WE 1: Water Efficient Landscaping4 points max
1.1 Use 50% reduction: rainwater, graywater, or recycled municipal
2 points
OR 1.2 NO potable water or NO irrigation
4 points
WE 2: InnovativeWastewater2 points max
Reduce potable water for sewage conveyance or treat to tertiary (50%)
2 points
WE 3: Water use reduction (all indoor fixtures; not irrigation)
3.1 Use 30% Reduction (20% is prerequisite v 3.0)
2 points
4 points max 3.2 Use 35% reduction adds 1 point
3.3 Use 40% reduction adds 1 point
WE Credits for LEED-NC: Maximum 10 points possible
Source: USGBC LEED for New Construction Rating System, 2009
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Example Commercial BuildingIndoor Rainwater Application (WE 2 Option 1; LEED-NC v 3.0)
Source: Building Green Futures (www.buildinggreenfutures.com)
http://www.sloanvalve.com
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CA Dual Plumbing Code 2010
• Air gap required (recycled and potable)
• Water disinfected to tertiary recycled standard (CA Dept Public Health; filtration/chlorine)
• Allowed structures specified by 13553 Water Code (no single-family residential)
Source: California Plumbing Code Chapter 16A-Part II, 2010
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Non-potable Indoor Use of Rainwater*
• Gutters & tank inlet with debris screen
• First flush/roof washer (first 10 gallons)
• Return elbow or calming inlet
• UV-resistant for above-ground
• Air gap or back-flow assembly (municipal vs. rainwater)
• Label pipes and fixtures
• Disinfection is not required
* Code Guide for Rainwater Harvesting; City of Portland for one and two family dwellings, 2001
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Rainwater Harvesting Overview
• Benefits of rainwater harvesting
• System components
• Water-harvesting earthworks
• Estimating supply & demand to size tanks
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Benefits of Rainwater Harvesting
COMMUNITY• Storm water management (reduces run off to
storm drains)• Reduces summer peak water demands
(conserves water)
INDIVIDUAL• Superior water for irrigation (soft, non-alkaline)• Lower water bills (1st tier)• Possible rebates/incentives (AB 1834)
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Components of Rainwater Harvesting for Irrigation
Roof catchment area
Gutters & downspout
StorageTank
OverflowPump
To drip system/hose
Source: Building Green Futures (www.buildinggreenfutures.com)
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Above-ground Tanks
Source: RainHarvest Systems
Source: BH Tanks Inc. Source: Bushman Tanks USA
Source: Tankworks Australia
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Below-ground Tanks
Source: Graf Rainwater Tanks
Source: Rainwater Collection Solutions
Source: Xerxes Fiberglass Tanks
Source: Atlantis Water Management
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Using Earthworks
Source: Building Green Futures (www.buildinggreenfutures.com)
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Landscape Features that Manage Stormwater
Source: EncinitasStormwaterManual, 2009
Photograph: City of Encinitas, Roadside GrassCrete parking
Source: SD County LID manual, 2007
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Sustainable Water Management
Source: Building Green Futures (www.buildinggreenfutures.com)
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Sizing a Rainwater Tank based on Supply & Demand
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Basic formula to calculate monthly or annual collection
volume in gallons:
SUPPLY (gallons) = Catchment Area (ft2) X Rainfall (ft)
X Runoff Coefficient X 7.48 gallons/ft3
Note: Runoff coefficient = 0.9 for a typical roof
Example scenario: a 2,000ft2 building:
2000ft2 x 0.83ft/yr x 90% x 7.48 gal/ft3 =
11,175 gallons per year!!
Basic formula to calculate monthly or annual irrigation
demand in gallons:
DEMAND (gallons) = (ETo X Plant Factor) X Area (ft2)
X 7.48 gallons/ft3
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Estimating Supply & Demand
Source: Building Green Futures (www.buildinggreenfutures.com)
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Outdoor Water Usage
• Drought-tolerant and native plant choices(and soil/mulch)
• Brief introduction to gray water for irrigation
• Rainwater Harvesting Design Strategies(for San Diego County)
• Example projects
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Graywater Code for California
• Ch 16A “Nonpotable Water Reuse Systems” added to 2007 California plumbing code August 4, 2009
• 1603A.1.1 Clothes Washer System and/or Single Fixture System: May be installed without a permit if in compliance
• May not result in ponding or run-off
• Design directs to irrigation and contained on site
• If released above-ground requires >/= 2” mulch
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Graywater System to Mulch Basins
www.yourhome.gov.au/technical/fs74.html
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Characteristics of Drought-tolerant Plants
Source: Building Green Futures (www.buildinggreenfutures.com)
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Resources for Drought-Tolerant and Native Plants
• Sunset Western Garden Book by Editors of Sunset Books and K. N. Brenzel; watering designation 1 or 2
• San Diego County Native Plants by James Lightner(2006, San Diego Flora)
• http://www.water.ca.gov/wateruseefficiency/docs/wucols00.pdf Water Use Classification of Landscape Species (University of California Cooperative Extension)
• http://www.bewaterwise.com/knowledge01.htmlCalifornia Friendly Garden resource (from MWD)
• http://www.thegarden.org/ Water conservation Garden at Cuyamaca College; bookshop & classes
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Project 1: An Above-ground System with a 550 gallon tank
Source: Building Green Futures (www.buildinggreenfutures.com)
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Project 2: An Above-ground System with (2) 2,000 gallon tanks and French drains to landscape
Source: Building Green Futures (www.buildinggreenfutures.com)
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Project 3: a Rainwater Pillow
Source: Building Green Futures (www.buildinggreenfutures.com)
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Source: Building Green Futures (www.buildinggreenfutures.com)
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Project 4: A Modular Underground Storage System
Source: Building Green Futures (www.buildinggreenfutures.com)
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Source: Building Green Futures (www.buildinggreenfutures.com)
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WE (min 3 pts) Credit Points Project item
WE 1: Water Reuse5 points max
1.1 Rainwater Harvesting SystemAnd/or
3 points outdoor1 point indoor
2 x 1700 gallon cisterns for irrigation only = 3
1.2 Graywater 1 point Clothes washer = 1
OR1.3 Municipal Recycled Water
3 pts max if use instead of1.1-1.2
WE 2: Irrigation 2.1 Hi-efficiency 3 points max
4 points max 2.2 3rd party 1 point max
OR 2.3 Reduce irrigation demand
4 points max
WE 3: Indoor Water Usage
3.1 Hi-efficiencyfixtures/fittings
3 points if all fixtures All fixtures meet standards = 3
6 points max 3.2 Very hi-efficiency (6 points max) TOTAL = 7
System size = Harvest area/Total Roof AreaStorage capacity = 0.62 gal/ft3 x Harvest areaTherefore 2,000 ft2 roof area min capacity = 620 gallons; max = 12,000 gallons
WE Credits for LEED-Homes: Maximum 15 points possible
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Project 5: Rainwater Harvesting at NC Schools: indoor and
outdoor usage
Diagrams and Photo Courtesy of Innovative Design (Raleigh, NC)
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Resources
• http://www.sandiego.gov/water/conservation
Rainwater harvesting information; residential water surveys (free)
• http://www.bewaterwise.com ; Rebates and incentives (So Cal Metropolitan Water District)
• http://socalwatersmart.com/index.php; Rebates/incentives
• http://www.harvesth2o.com/ ; Online rainwater harvesting community
• http://www.arcsa.org/Rainwater-10-09.pdf; Rainwater Catchment Standards ARCSA and ASPE
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Resources; continued• http://www.epa.gov/npdes/pubs/gi_municha
ndbook_harvesting.pdf; EPA Rainwater Harvesting Guidelines
• http://www.whollyh2o.org; California’s Integrated Water Reuse Management Center
• http://www.h2ouse.org; California’s Urban Water Conservation Council
• http://www.oasisdesign.net/greywater/law/california/; California Graywater Policy Center
• Rainwater Harvesting for Drylands vol 1-3 by Brad Lancaster, Rainsource Press (2005-2011)
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IF we combine low water use fixtures with water reuse indoors and outdoors
we can:
• Reduce wastewater and stormwater runoff
• Reduce use of potable water
• Increase water reuse
• Restore natural hydrologic cycle
• Preserve freshwater for future generations